Question

5+10+15+...+2005+2010=?​

Answer 1

n=(u-p):r+1

n=(2010-5):5+1

n=2005:5+1

n=401+1

n=402

S=(u+p)×n:2

S=(2010+5)×402:2

S=2015×402:2

S=2015×201

S=405015

Answer 2

Raspuns:

5+10+15+...+2005+2010 =

5 * ( 1 + 2 + 3 + ... + 401 + 402) =

$S_{1}$ = (402 * 401) : 2

$S_{1}$ = 80601

$S_{2}$ = 80601 * 5

$S_{2}$ = 403005